Conventionally, battery voltage is an indicator to determine whether a battery has entered a low battery state. That is, when the battery voltage is detected to be lower than a threshold, the battery is considered as being in the low battery state.
However, after a battery enters the low battery state, the battery voltage would rapidly decline, thus the remaining battery life is extremely limited. This is unfavorable for applications such as wearable devices for long time usages, environmental sensors, or other miniature devices.
Therefore, there is a need to provide a technology capable of warning that a battery is about to enter the low battery state in advance.